using System;

using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;

namespace Org.BouncyCastle.Asn1.Cms
{
	public class PasswordRecipientInfo
		: Asn1Encodable
	{
		private readonly DerInteger				version;
		private readonly AlgorithmIdentifier	keyDerivationAlgorithm;
		private readonly AlgorithmIdentifier	keyEncryptionAlgorithm;
		private readonly Asn1OctetString		encryptedKey;

		public PasswordRecipientInfo(
			AlgorithmIdentifier	keyEncryptionAlgorithm,
			Asn1OctetString		encryptedKey)
		{
			this.version = new DerInteger(0);
			this.keyEncryptionAlgorithm = keyEncryptionAlgorithm;
			this.encryptedKey = encryptedKey;
		}

		public PasswordRecipientInfo(
			AlgorithmIdentifier	keyDerivationAlgorithm,
			AlgorithmIdentifier	keyEncryptionAlgorithm,
			Asn1OctetString		encryptedKey)
		{
			this.version = new DerInteger(0);
			this.keyDerivationAlgorithm = keyDerivationAlgorithm;
			this.keyEncryptionAlgorithm = keyEncryptionAlgorithm;
			this.encryptedKey = encryptedKey;
		}

		public PasswordRecipientInfo(
			Asn1Sequence seq)
		{
			version = (DerInteger) seq[0];

			if (seq[1] is Asn1TaggedObject)
			{
				keyDerivationAlgorithm = AlgorithmIdentifier.GetInstance((Asn1TaggedObject) seq[1], false);
				keyEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(seq[2]);
				encryptedKey = (Asn1OctetString) seq[3];
			}
			else
			{
				keyEncryptionAlgorithm = AlgorithmIdentifier.GetInstance(seq[1]);
				encryptedKey = (Asn1OctetString) seq[2];
			}
		}

		/**
		 * return a PasswordRecipientInfo object from a tagged object.
		 *
		 * @param obj the tagged object holding the object we want.
		 * @param explicitly true if the object is meant to be explicitly
		 *              tagged false otherwise.
		 * @exception ArgumentException if the object held by the
		 *          tagged object cannot be converted.
		 */
		public static PasswordRecipientInfo GetInstance(
			Asn1TaggedObject	obj,
			bool				explicitly)
		{
			return GetInstance(Asn1Sequence.GetInstance(obj, explicitly));
		}

		/**
		 * return a PasswordRecipientInfo object from the given object.
		 *
		 * @param obj the object we want converted.
		 * @exception ArgumentException if the object cannot be converted.
		 */
		public static PasswordRecipientInfo GetInstance(
			object obj)
		{
			if (obj == null || obj is PasswordRecipientInfo)
				return (PasswordRecipientInfo) obj;

			if (obj is Asn1Sequence)
				return new PasswordRecipientInfo((Asn1Sequence) obj);

			throw new ArgumentException("Invalid PasswordRecipientInfo: " + obj.GetType().Name);
		}

		public DerInteger Version
		{
			get { return version; }
		}

		public AlgorithmIdentifier KeyDerivationAlgorithm
		{
			get { return keyDerivationAlgorithm; }
		}

		public AlgorithmIdentifier KeyEncryptionAlgorithm
		{
			get { return keyEncryptionAlgorithm; }
		}

		public Asn1OctetString EncryptedKey
		{
			get { return encryptedKey; }
		}

		/**
		 * Produce an object suitable for an Asn1OutputStream.
		 * <pre>
		 * PasswordRecipientInfo ::= Sequence {
		 *   version CMSVersion,   -- Always set to 0
		 *   keyDerivationAlgorithm [0] KeyDerivationAlgorithmIdentifier
		 *                             OPTIONAL,
		 *  keyEncryptionAlgorithm KeyEncryptionAlgorithmIdentifier,
		 *  encryptedKey EncryptedKey }
		 * </pre>
		 */
		public override Asn1Object ToAsn1Object()
		{
			Asn1EncodableVector v = new Asn1EncodableVector(version);

			if (keyDerivationAlgorithm != null)
			{
				v.Add(new DerTaggedObject(false, 0, keyDerivationAlgorithm));
			}

			v.Add(keyEncryptionAlgorithm, encryptedKey);

			return new DerSequence(v);
		}
	}
}
